Ron Solberg or maybe Willie via EV (I can't tell which) wrote:
Well.... back to your question. Presumed to be "Can I clean up a square wave inverter power to something acceptable to my onboard Tesla charger?" I'm out of my depth. Surely Lee has ideas. In the past, I believe I've seen him recommend a motor-generator...
There are lots of solutions. Which one is "best" depends on what you've got, what you want to spend, and how good it needs to be.
A motor-generator is perhaps the oldest way to go about it. The motor is chosen based on what input voltage you have (AC or DC). The generator ("alternator" if it outputs AC) is chosen for the voltage you want. This is still a good solution for very high power, very clean sinewaves, or 3-phase power. A motor-generator is also good at starting heavy loads, like big motors.
The price isn't necessarily unreasonable if you buy surplus. I have a Westinghouse 240vdc in, 240vac 60Hz 15/30 KW continuous/intermittent 3-phase out unit that cost me $300. It weighs about 250 lbs.
Next newer approach: There are filters that can "clean up" the output of a square wave ("modified sine wave") inverter. One simple one is called an Ott filter. Basically, it's some big inductors and capacitors. They form resonant circuits to filter out the 3rd and 5th harmonics, and so make a square wave look a lot closer to a sine wave. I have one that converts 120vac 600w into a reasonable sinewave. It's about the size of a shoebox and weighs 15 lbs.
Beyond this, if you really need a sinewave output, you probably have to use a commercial sinewave inverter. Since these are expensive, you will probably have to size it to power only the loads that are "particular" about the power they get.
If you're using PV power (DC input) to charge an EV (DC output), then what you really want is a big DC/DC converter. A conventional EV series motor controller can be used for this. It's basically a step-down DC/DC converter with the output filter missing (the motor substitutes for it). To use a motor controller as a general-purpose battery charger, you need a big series inductor (the field of a DC series motor, for example), and a big bank of filter capacitors (the batteries you are charging can be most of this).
-- Fools ignore complexity. Pragmatists suffer it. The wise avoid it. Geniuses remove it. -- Alan Perlis, "Epigrams on Programming" -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
